Classic X-Men comic books, later retitled as X-Men Classic, reprints the earliest X-Men stories. The first issue was a partial reprint of Giant-Size X-Men #1, and the other issues reprinted Uncanny X-Men #94-206, with the exception of the "Days of Future Past" story from issues #141 and #142. Classic X-Men often printed additional back-up stories further delving into and explaining the original stories.